1. Field of the Invention
The present invention relates to a printer for printing on a sheet. The printer of the present invention is generic name of a device comprising: a sheet sending mechanism which successively sends cut sheets; and a printing mechanism which successively prints characters, graphics, photographic images or the like on the sheets sent by the sheet sending mechanism. Not only a printer with a single function, but also a copying device, a facsimile device, a composite device (or a multifunction device) and the like comprising the sheet sending mechanism and printing mechanism also are the printer described herein.
In one type of printer of the present invention, a sheet sending mechanism is operated in a plurality of operation modes. In order to operate the sheet sending mechanism in the plurality of operation modes, the printer of the present invention comprises a plurality of force transmitting paths and a selecting mechanism for activating any of the force transmitting paths.
Other type of the printer of the present invention comprises a plurality of sheet sending mechanisms. In order to operate the plurality of sheet sending mechanisms, the printer of the present invention comprises a plurality of force transmitting paths and a selecting mechanism for activating any of the force transmitting paths.
Yet further type of the printer of the present invention comprises a maintaining mechanism for a printing head. In order to operate the maintaining mechanism and the sheet sending mechanism, the printer of the present invention comprises a plurality of force transmitting paths and a selecting mechanism for activating any of the force transmitting paths.
2. Description of the Related Art
There has been conventionally known printers with single function which can print on a plurality of sizes of sheets, and printers such as copying machines, facsimile devices, composite devices, and the like. These types of printers use a plurality of cassettes that store a plurality of sheets having the same size in a stacked manner. The sizes of the sheets stored in each cassette are different from one another. The plurality of cassettes are stored in the printer in a stacked manner. A cassette is selected in accordance with a command for designating the size of the sheet or an image command. The uppermost sheet of the sheets stacked in a selected cassette is sent by a supply roller. The sheet which is sent from the cassette is conveyed toward a printing region secured in a lower section of a printing head via a conveying path. This type of printer comprises a plurality of sheet sending mechanisms.
As disclosed in Japanese Patent Application Laid-Open Publication No. H8-174958 or Japanese Patent Application Laid-Open Publication No. 2003-89244, there is known a printer which comprises an ink jet type printing head for printing a graphic pattern configured with dot patterns. In the ink-jet type printing head, ejection failure of the inks occurs due to the structure of the printing head, thus the ink-jet type printing head is provided with a maintaining mechanism in the printer in order to cope with such ink ejection failure. The printing head is moved to a position facing the maintaining mechanism, and the printing head is treated by the maintaining mechanism at this position. This type of printer comprises the maintaining mechanism and the sheet sending mechanism.
Among printers, there is a printer which can switch between a mode for continuously and successively sending sheets from a cassette and a mode for intermittently sending sheets from a cassette. This type of printer comprises a plurality of driving force transmitting paths in order to operate the sheet sending mechanism using a plurality of operation modes.
A driving force needs to be transmitted to the sheet sending mechanism or maintaining mechanism.
The printer disclosed in Japanese Patent Application Laid-Open Publication No. H8-174958 employs a structure of moving a kick member by using a movement of a carriage which moves the printing head. By means of a movement of the kick member, switching is made between a state in which an idle gear is engaged with a gear driving the maintaining mechanism, and a state in which the idle gear is engaged with a gear driving a sheet sending roller. In the printer disclosed in Japanese Patent Application Laid-Open Publication No. H8-174958, when the carriage is separated from a purge position, the idle gear is engaged with the gear driving the maintaining mechanism. When the carriage is at the purge position, the idle gear is engaged with the purge gear.
The printer disclosed in Japanese Patent Application Laid-Open Publication No. 2003-89244 comprises: a supply gear which rotates a supply gear sending one sheet from a plurality of stacked sheets; a feed gear which rotates a feed-in roller sending a sheet to a printing region and a feed-out roller drawing the sheet from the printing region; a maintenance gear which drives a maintaining mechanism; and a drive motor. Also, there is provided a slider which moves after the carriage moves so that power is transmitted to any of the supply gear, feed gear, and maintenance gear from the drive motor. The slider comprises a switching gear. When the slider slides, the switching gear is engaged with any one of the supply gear, feed gear, and maintenance gear.
In this printer, if the carriage is positioned within a width of a sheet, the switching gear and supply gear are engaged with the feed gear. When the printer executes a maintenance work, the carriage is moved to a maintenance position. Accordingly, the switching gear is engaged with the maintenance gear. When the printer discharges the last page of the sheets, the carriage is moved to an intermediate position between the abovementioned two positions. Accordingly, the switching gear is engaged with the feed gear.